From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757435AbaGWIy0 (ORCPT ); Wed, 23 Jul 2014 04:54:26 -0400 Received: from mail-ie0-f172.google.com ([209.85.223.172]:54962 "EHLO mail-ie0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756127AbaGWIyU (ORCPT ); Wed, 23 Jul 2014 04:54:20 -0400 Date: Wed, 23 Jul 2014 09:54:11 +0100 From: Lee Jones To: Jassi Brar Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, ks.giri@samsung.com, arnd@arndb.de, ijc@hellion.org.uk, mark.rutland@arm.com, robh@kernel.org, pawel.moll@arm.com, courtney.cavin@sonymobile.com, mporter@linaro.org, slapdau@yahoo.com.au, lftan.linux@gmail.com, loic.pallardy@st.com, s-anna@ti.com, ashwin.chaugule@linaro.org, bjorn@kryo.se, patches@linaro.org, t.takinishi@jp.fujitsu.com, broonie@linaro.org, khilman@linaro.org, mollie.wu@linaro.org, andy.green@linaro.org Subject: Re: [PATCHv9 2/4] mailbox: Introduce framework for mailbox Message-ID: <20140723085411.GG23210@lee--X1> References: <1406055250-29159-1-git-send-email-jaswinder.singh@linaro.org> <1406055374-29275-1-git-send-email-jaswinder.singh@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1406055374-29275-1-git-send-email-jaswinder.singh@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 23 Jul 2014, Jassi Brar wrote: > Introduce common framework for client/protocol drivers and > controller drivers of Inter-Processor-Communication (IPC). > > Client driver developers should have a look at > include/linux/mailbox_client.h to understand the part of > the API exposed to client drivers. > Similarly controller driver developers should have a look > at include/linux/mailbox_controller.h > > Signed-off-by: Jassi Brar > --- > MAINTAINERS | 8 + > drivers/mailbox/Makefile | 4 + > drivers/mailbox/mailbox.c | 467 +++++++++++++++++++++++++++++++++++++ > include/linux/mailbox_client.h | 45 ++++ > include/linux/mailbox_controller.h | 131 +++++++++++ > 5 files changed, 655 insertions(+) > create mode 100644 drivers/mailbox/mailbox.c > create mode 100644 include/linux/mailbox_client.h > create mode 100644 include/linux/mailbox_controller.h After a _quick_ look through: > diff --git a/MAINTAINERS b/MAINTAINERS > index 61a8f48..9f225d2 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -5672,6 +5672,14 @@ S: Maintained > F: drivers/net/macvlan.c > F: include/linux/if_macvlan.h > > +MAILBOX API > +M: Jassi Brar Gmail? > +L: linux-kernel@vger.kernel.org > +S: Maintained > +F: drivers/mailbox/ > +F: include/linux/mailbox_client.h > +F: include/linux/mailbox_controller.h > + [...] > diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c > new file mode 100644 > index 0000000..99c0d23 > --- /dev/null > +++ b/drivers/mailbox/mailbox.c > @@ -0,0 +1,467 @@ > +/* > + * Mailbox: Common code for Mailbox controllers and users > + * > + * Copyright (C) 2013-2014 Linaro Ltd. > + * Author: Jassi Brar (C) Linaro, but you've supplied your Gmail? > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define TXDONE_BY_IRQ (1 << 0) /* controller has remote RTR irq */ > +#define TXDONE_BY_POLL (1 << 1) /* controller can read status of last TX */ > +#define TXDONE_BY_ACK (1 << 2) /* S/W ACK recevied by Client ticks the TX */ BIT(0), BIT(1), BIT(2). > +static LIST_HEAD(mbox_cons); > +static DEFINE_MUTEX(con_mutex); > + > +static int add_to_rbuf(struct mbox_chan *chan, void *mssg) > +{ > + int idx; > + unsigned long flags; > + > + spin_lock_irqsave(&chan->lock, flags); > + > + /* See if there is any space left */ > + if (chan->msg_count == MBOX_TX_QUEUE_LEN) { > + spin_unlock_irqrestore(&chan->lock, flags); > + return -ENOMEM; Doesn't -ENOMEM signify out-of-system-memory, rather than a buffer has been filled? I'm thinking ENOBUFS would be more appropriate. > + } > + > + idx = chan->msg_free; > + chan->msg_data[idx] = mssg; > + chan->msg_count++; > + > + if (idx == MBOX_TX_QUEUE_LEN - 1) > + chan->msg_free = 0; > + else > + chan->msg_free++; > + > + spin_unlock_irqrestore(&chan->lock, flags); > + > + return idx; > +} > + > +static void msg_submit(struct mbox_chan *chan) > +{ > + unsigned count, idx; > + unsigned long flags; > + void *data; > + int err; > + > + spin_lock_irqsave(&chan->lock, flags); > + > + if (!chan->msg_count || chan->active_req) { > + spin_unlock_irqrestore(&chan->lock, flags); > + return; > + } You could reduce by a line here if you use a goto, to jump down to the other spin_unlock*(). > + count = chan->msg_count; > + idx = chan->msg_free; > + if (idx >= count) > + idx -= count; > + else > + idx += MBOX_TX_QUEUE_LEN - count; > + > + data = chan->msg_data[idx]; > + > + /* Try to submit a message to the MBOX controller */ > + err = chan->mbox->ops->send_data(chan, data); > + if (!err) { > + chan->active_req = data; > + chan->msg_count--; > + } How do we let the caller know if an error occured? > + spin_unlock_irqrestore(&chan->lock, flags); > +} [...] > +static void poll_txdone(unsigned long data) > +{ > + struct mbox_controller *mbox = (struct mbox_controller *)data; > + bool txdone, resched = false; > + int i; > + > + for (i = 0; i < mbox->num_chans; i++) { > + struct mbox_chan *chan = &mbox->chans[i]; > + > + if (chan->active_req && chan->cl) { > + resched = true; > + txdone = chan->mbox->ops->last_tx_done(chan); You should probably add a comment somewhere that this operation is compulsory. Same for all of the other mandatory call-backs. > + if (txdone) > + tx_tick(chan, 0); > + } > + } > + > + if (resched) > + mod_timer(&mbox->poll, jiffies + > + msecs_to_jiffies(mbox->period)); > +} [...] > +/** > + * mbox_send_message - For client to submit a message to be > + * sent to the remote. > + * @chan: Mailbox channel assigned to this client. > + * @mssg: Client specific message typecasted. > + * > + * For client to submit data to the controller destined for a remote > + * processor. If the client had set 'tx_block', the call will return > + * either when the remote receives the data or when 'tx_tout' millisecs > + * run out. > + * In non-blocking mode, the requests are buffered by the API and a > + * non-negative token is returned for each queued request. If the request > + * is not queued, a negative token is returned. Upon failure or successful > + * TX, the API calls 'tx_done' from atomic context, from which the client > + * could submit yet another request. > + * The pointer to message should be preserved until it is sent > + * over the chan, i.e, tx_done() is made. > + * This function could be called from atomic context as it simply > + * queues the data and returns a token against the request. > + * > + * Return: Non-negative integer for successful submission (non-blocking mode) > + * or transmission over chan (blocking mode). > + * Negative value denotes failure. > + */ > +int mbox_send_message(struct mbox_chan *chan, void *mssg) > +{ > + int t; > + > + if (!chan || !chan->cl) > + return -EINVAL; > + > + t = add_to_rbuf(chan, mssg); > + if (t < 0) { > + pr_err("Try increasing MBOX_TX_QUEUE_LEN\n"); Really? > + return t; > + } > + > + msg_submit(chan); > + > + reinit_completion(&chan->tx_complete); > + > + if (chan->txdone_method == TXDONE_BY_POLL) > + poll_txdone((unsigned long)chan->mbox); > + > + if (chan->cl->tx_block && chan->active_req) { > + unsigned long wait; > + int ret; > + > + if (!chan->cl->tx_tout) /* wait for ever */ s/for ever/forever > + wait = msecs_to_jiffies(3600000); What will this do? Will it block the system forever? > + else > + wait = msecs_to_jiffies(chan->cl->tx_tout); > + > + ret = wait_for_completion_timeout(&chan->tx_complete, wait); > + if (ret == 0) { > + t = -EIO; > + tx_tick(chan, -EIO); > + } > + } > + > + return t; > +} > +EXPORT_SYMBOL_GPL(mbox_send_message); > + > +/** > + * mbox_request_channel - Request a mailbox channel. > + * @cl: Identity of the client requesting the channel. > + * @index: Index of mailbox specifier in 'mboxes' property. > + * > + * The Client specifies its requirements and capabilities while asking for > + * a mailbox channel. It can't be called from atomic context. > + * The channel is exclusively allocated and can't be used by another > + * client before the owner calls mbox_free_channel. > + * After assignment, any packet received on this channel will be > + * handed over to the client via the 'rx_callback'. > + * The framework holds reference to the client, so the mbox_client > + * structure shouldn't be modified until the mbox_free_channel returns. > + * > + * Return: Pointer to the channel assigned to the client if successful. > + * ERR_PTR for request failure. > + */ > +struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index) > +{ > + struct device *dev = cl->dev; > + struct mbox_controller *mbox; > + struct of_phandle_args spec; > + struct mbox_chan *chan; > + unsigned long flags; > + int ret; > + > + if (!dev || !dev->of_node) { > + pr_debug("%s: No owner device node\n", __func__); Are you sure you want all of this debug prints in the final version? > + return ERR_PTR(-ENODEV); > + } > + > + mutex_lock(&con_mutex); > + > + if (of_parse_phandle_with_args(dev->of_node, "mboxes", > + "#mbox-cells", index, &spec)) { > + pr_debug("%s: can't parse \"mboxes\" property\n", __func__); How you have a 'struct device' to play with, can't you use dev_dbg() and friends? > + mutex_unlock(&con_mutex); > + return ERR_PTR(-ENODEV); > + } > + > + chan = NULL; Do this during declaration. > + list_for_each_entry(mbox, &mbox_cons, node) > + if (mbox->dev->of_node == spec.np) { > + chan = mbox->of_xlate(mbox, &spec); > + break; > + } > + > + of_node_put(spec.np); > + > + if (!chan || chan->cl || !try_module_get(mbox->dev->driver->owner)) { > + pr_debug("%s: mailbox not free\n", __func__); > + mutex_unlock(&con_mutex); > + return ERR_PTR(-EBUSY); > + } > + > + spin_lock_irqsave(&chan->lock, flags); > + chan->msg_free = 0; > + chan->msg_count = 0; > + chan->active_req = NULL; > + chan->cl = cl; > + init_completion(&chan->tx_complete); > + > + if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) > + chan->txdone_method |= TXDONE_BY_ACK; > + > + spin_unlock_irqrestore(&chan->lock, flags); > + > + ret = chan->mbox->ops->startup(chan); > + if (ret) { > + pr_err("Unable to startup the chan (%d)\n", ret); > + mbox_free_channel(chan); > + chan = ERR_PTR(ret); > + } > + > + mutex_unlock(&con_mutex); > + return chan; > +} > +EXPORT_SYMBOL_GPL(mbox_request_channel); > + > +/** > + * mbox_free_channel - The client relinquishes control of a mailbox > + * channel by this call. > + * @chan: The mailbox channel to be freed. > + */ > +void mbox_free_channel(struct mbox_chan *chan) > +{ > + unsigned long flags; > + > + if (!chan || !chan->cl) > + return; > + > + chan->mbox->ops->shutdown(chan); > + > + /* The queued TX requests are simply aborted, no callbacks are made */ > + spin_lock_irqsave(&chan->lock, flags); > + chan->cl = NULL; > + chan->active_req = NULL; > + if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK)) > + chan->txdone_method = TXDONE_BY_POLL; Unless you're leaving it there for clarity, you can drop the "TXDONE_BY_POLL |" from if(). > + module_put(chan->mbox->dev->driver->owner); > + spin_unlock_irqrestore(&chan->lock, flags); > +} > +EXPORT_SYMBOL_GPL(mbox_free_channel); > + > +static struct mbox_chan * > +of_mbox_index_xlate(struct mbox_controller *mbox, > + const struct of_phandle_args *sp) > +{ > + int ind = sp->args[0]; > + > + if (ind >= mbox->num_chans) > + return NULL; > + > + return &mbox->chans[ind]; > +} > + > +/** > + * mbox_controller_register - Register the mailbox controller > + * @mbox: Pointer to the mailbox controller. > + * > + * The controller driver registers its communication channels > + */ > +int mbox_controller_register(struct mbox_controller *mbox) > +{ > + int i, txdone; > + > + /* Sanity check */ > + if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans) > + return -EINVAL; > + > + if (mbox->txdone_irq) > + txdone = TXDONE_BY_IRQ; > + else if (mbox->txdone_poll) > + txdone = TXDONE_BY_POLL; > + else /* It has to be ACK then */ > + txdone = TXDONE_BY_ACK; > + > + if (txdone == TXDONE_BY_POLL) { > + mbox->poll.function = &poll_txdone; > + mbox->poll.data = (unsigned long)mbox; > + init_timer(&mbox->poll); > + } Can't you put this in the statement above? > + for (i = 0; i < mbox->num_chans; i++) { > + struct mbox_chan *chan = &mbox->chans[i]; > + > + chan->cl = NULL; > + chan->mbox = mbox; > + chan->txdone_method = txdone; > + spin_lock_init(&chan->lock); > + } > + > + if (!mbox->of_xlate) > + mbox->of_xlate = of_mbox_index_xlate; > + > + mutex_lock(&con_mutex); > + list_add_tail(&mbox->node, &mbox_cons); > + mutex_unlock(&con_mutex); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(mbox_controller_register); > + > +/** > + * mbox_controller_unregister - Unregister the mailbox controller > + * @mbox: Pointer to the mailbox controller. > + */ > +void mbox_controller_unregister(struct mbox_controller *mbox) > +{ > + int i; > + > + if (!mbox) > + return; > + > + mutex_lock(&con_mutex); > + > + list_del(&mbox->node); > + > + for (i = 0; i < mbox->num_chans; i++) > + mbox_free_channel(&mbox->chans[i]); > + > + if (mbox->txdone_poll) > + del_timer_sync(&mbox->poll); > + > + mutex_unlock(&con_mutex); > +} > +EXPORT_SYMBOL_GPL(mbox_controller_unregister); > diff --git a/include/linux/mailbox_client.h b/include/linux/mailbox_client.h > new file mode 100644 > index 0000000..0f8cba6 > --- /dev/null > +++ b/include/linux/mailbox_client.h > @@ -0,0 +1,45 @@ > +/* > + * Copyright (C) 2013-2014 Linaro Ltd. > + * Author: Jassi Brar > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > + > +#ifndef __MAILBOX_CLIENT_H > +#define __MAILBOX_CLIENT_H > + > +#include device.h > +struct mbox_chan; > + > +/** > + * struct mbox_client - User of a mailbox > + * @dev: The client device > + * @tx_block: If the mbox_send_message should block until data is > + * transmitted. > + * @tx_tout: Max block period in ms before TX is assumed failure > + * @knows_txdone: If the client could run the TX state machine. Usually > + * if the client receives some ACK packet for transmission. > + * Unused if the controller already has TX_Done/RTR IRQ. > + * @rx_callback: Atomic callback to provide client the data received > + * @tx_done: Atomic callback to tell client of data transmission > + */ > +struct mbox_client { > + struct device *dev; > + bool tx_block; > + unsigned long tx_tout; > + bool knows_txdone; > + > + void (*rx_callback)(struct mbox_client *cl, void *mssg); > + void (*tx_done)(struct mbox_client *cl, void *mssg, int r); > +}; > + > +struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index); > +int mbox_send_message(struct mbox_chan *chan, void *mssg); > +void mbox_client_txdone(struct mbox_chan *chan, int r); /* atomic */ > +bool mbox_client_peek_data(struct mbox_chan *chan); /* atomic */ > +void mbox_free_channel(struct mbox_chan *chan); /* may sleep */ > + > +#endif /* __MAILBOX_CLIENT_H */ > diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h > new file mode 100644 > index 0000000..976c4ed > --- /dev/null > +++ b/include/linux/mailbox_controller.h > @@ -0,0 +1,131 @@ > +/* > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > + > +#ifndef __MAILBOX_CONTROLLER_H > +#define __MAILBOX_CONTROLLER_H > + > +#include completion.h device.h timer.h Etc. [...] -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog